The overall objective of the study is to conduct an observational study involving intensive care unit patients receiving mechanical ventilation and determine if there are differences in diaphragm thickness ultrasound measurements during expiratory and inspiratory phases in a controlled and spontaneous mode. For patients receiving sedatives, an additional set of measurements will be taken during a standard of care interruption of sedatives
In this study diaphragm ultrasound measurements at end-expiration and peak inspiration phases in assist control and pressure support mode in consented patients admitted to the medical intensive care unit. One-time measurements will be obtained during the first 48hrs that the patients are receiving mechanical ventilation. In patients receiving sedatives, additional measurements will be taken after an interruption of sedatives. Measurements will be compared between modes and on assist-control before and after an interruption of sedatives. Three consecutive images will be obtained by an investigator that is blinded to the mode (controlled vs. spontaneous). Once measurements are obtained, a second investigator will switch to the other mode (controlled vs. spontaneous) and the blinded investigator will obtain three consecutive images after the patient has adjusted to the subsequent mode (one minute). Tidal volumes will be matched between modes as close as possible. The order of modes to ultrasound (controlled then spontaneous or spontaneous then controlled) will be determined by the non-blinded second investigator. Once the ultrasound measurements are obtained by the research team, image acquisition is concluded for the enrolled patient. The ventilator will be programmed back to the original settings determined by the medical ICU team. The hypothesis is that the end-expiration diaphragm ultrasound measurement will be thicker in spontaneous mode than controlled mode.
Study Type
OBSERVATIONAL
Enrollment
66
Diaphragm ultrasound measurements (end expiration and peak inspiration thickness) will be performed in assist control mode and pressure support mode mechanical ventilation in each participant. The participant will thus serve as his/her own control for these interventions.
The University of Chicago Medical Center
Chicago, Illinois, United States
End expiratory diaphragm thickness in controlled and spontaneous modes
Diaphragm ultrasound measurement at end expiration in assist control mode and pressure support mode
Time frame: Less than 48 hours after mechanical ventilation
Thickening fraction in controlled and spontaneous modes
Diaphragm ultrasound measurement at end expiration and inspiration to calculate thickening fraction = (peak inspiration thickness - end expiration thickness)/end expiration thickness in assist control and pressure support mode ventilation
Time frame: Less than 48 hours after mechanical ventilation
Variance in peak inspiration thickness in controlled and spontaneous modes
Diaphragm ultrasound measurement at peak inspiration in assist control and pressure support
Time frame: Less than 48 hours after mechanical ventilation
p0.1 measurements in controlled and spontaneous modes
A measure of respiratory drive obtained from the ventilator in assist control and pressure support
Time frame: Less than 48 hours after mechanical ventilation
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